Dosimetric end-to-end verification devices, systems, and methods

ABSTRACT

Dosimetrical end-to-end quality assurance devices, systems, and methods for radiation devices using X-ray imaging, optical surface imaging, and electromagnetic navigational systems to position the quality assurance device either absolute or relative in space.

FIELD

The present disclosure relates generally to radiation therapy systems,devices, and methods, and more particularly to quality assuranceend-to-end verification devices for the testing, calibration, andvalidation of radiation treatment systems, devices, and methods.

BACKGROUND

In radiosurgery or radiotherapy (collectively referred to as radiationtreatment), very intense and precisely collimated doses of radiation aredelivered to the target region in the body of a patient in order totreat or destroy lesions. Typically, the target region is comprised of avolume of tumorous tissue. Radiation treatment requires an accuratespatial localization of the targeted lesions. Stereotactic radiosurgery(SRS) is a specific type of image-based treatment, which delivers a highdose of radiation during a single session. Because a single radiosurgerydose is more damaging than multiple fractionated doses, the target areamust be precisely located.

In general, radiation treatments consist of several phases. First, aprecise three-dimensional (3D) map of the anatomical structures in thearea of interest (head, body, etc.) is constructed using any one of (orcombinations thereof) a computed tomography (CT), cone-beam computedtomography (CBCT), magnetic resonance imaging (MRI), positron emissiontomography (PET), 3D rotational angiography (3DRA), ultrasoundtechniques, single photon emission tomography (SPECT), or biplanardigital subtraction angiography (DSA). This determines the exactcoordinates of the target within the anatomical structure, namely,locates the tumor or abnormality within the body and defines its exactshape and size. Second, a motion path for the radiation beam is computedto deliver a dose distribution that the surgeon and/or radiationoncologist finds acceptable, taking into account a variety of medicalconstraints. During this phase, a team of specialists develop atreatment plan using special computer software to optimally irradiatethe tumor and minimize dose to the surrounding normal tissue bydesigning beams of radiation to converge on the target area fromdifferent angles and planes. Third, the radiation treatment plan isexecuted. During this phase, the radiation dose is delivered to thepatient according to the prescribed treatment plan. The imagingmodalities in each of these steps arc configured to operate withinprescribed modes of operation for each type of scan performed.

Generally, quality assurance (QA) and verification protocols areinstituted for each stage of the radiation treatment process. Theperformance of the respective radiation treatment devices, theirgenerated images, and the transfer of those images across digitalnetworks are calibrated and tested by phantom assemblies and deviceswhich, when imaged by the respective imaging modality, generate imagesthat are representative, familiar, and logical to the structure andconfiguration of the phantom. Systematic testing and measurement of theimages should produce measurement values that fall within the range ofexpected and legally acceptable values which indicate that the imagingdevice operates within normal or acceptable levels of performance.

Existing verification phantoms include CT phantoms, slab geometryphantoms, and anthromorphic phantoms. CT phantoms are used for checkingthe CT number relative electron density (RED) conversion, the radiationbeam geometry assessments, the digitally reconstructed radiograph (DRR)generation, and multiplanar reconstruction. Slab geometry phantoms areused for film dosimetry and corrections for inhomogeneous geometries.Anthromorphic phantoms are used for dosimetric measurements of typicalor special treatment techniques. Each of these phantoms is designed tofulfill a particular verification function at a particular stage of thetreatment process.

Currently there is no single universal verification phantom availablethat can provide end-to-end verification, and which can besimultaneously used with a range of imaging modalities to facilitateimage based positioning and monitoring, as well as dosimetric analysisof the delivered dose distribution.

SUMMARY

Embodiments of the present invention provide a universal phantomassembly that can be used to simulate the entire treatment procedure:scanning, targeting, planning, and radiation dose delivery.

Embodiments of the present invention provide a single universalverification phantom that can provide end-to-end verification, and whichcan be simultaneously used with a range of imaging modalities tofacilitate image based positioning and monitoring, as well as dosimetricanalysis of the delivered dose distribution.

Embodiments of the present invention provide a phantom assembly that canbe used to simulate every stage of a radiation treatment process that apatient would be exposed to, including CT scan, MRI scan, SPECT/PET,biplanar and rotational angiography, isocenter determination, doseplanning and calculation, positioning of the phantom (patient) at thetreatment device using various kinds of positioning and monitoringsystems (kV, MV, computed tomography (CT), cone-beam computed tomography(CBCT), digital tomosynthesis (DTS), magnetic resonance imaging (MRI),optical surface monitoring system, Calypso), irradiation using thedetermined treatment plan (volumetric modulated arc therapy (VMAT),intensity-modulated radiation therapy (IMRT), conformal arc, cones,high-definition multileaf collimator (HDMLC), multileaf collimator(MLC), three-dimensional conformal radiation therapy (3DCRT) and anycombinations), and analysis of the measured dose distribution in orderto compare the measured dose distribution with the calculated one interms of dose volume/area parameters, or in terms of dose localizationaccuracy to determine the dosimetric isocenter.

Embodiments of the present invention provide a universal verificationphantom assembly that allows testing and validating the measurementaccuracy of two-dimensional (2D) and three-dimensional (3D) imagemeasurement devices and tools installed on medical imaging devices whichare involved in every stage of the radiation treatment process, as wellas verification of the measurement accuracy of digital image viewingstations that include diagnostic, clinical review, internet browser andteleradiology network of transferred medical diagnostic image systems.

Embodiments of the present invention provide a three-dimensional phantomassembly that can be used to independently verify the phantom orisocenter position by the use of various positioning systems availableon the treatment device, and is able to facilitate image basedpositioning of the phantom using (kV, MV, computed tomography (CT),cone-beam computed tomography (CBCT), digital tomosynthesis (DTS),magnetic resonance imaging (MRI), optical surface monitoring system,Calypso monitoring).

BRIEF DESCRIPTION OF DRAWINGS

Embodiments will hereinafter be described with reference to theaccompanying drawings, which have not necessarily been drawn to scale.Where applicable, some features may not be illustrated to assist in theillustration and description of underlying features.

FIG. 1 is a perspective view of a verification phantom in a closedposition according to various embodiments of the disclosed subjectmatter.

FIGS. 2-4 are perspective views of a verification phantom in an openposition according to one or more embodiments of the disclosed subjectmatter.

FIG. 5 is a top plan view of a verification phantom according to one ormore embodiments of the disclosed subject matter.

FIG. 6 is a side plan view of a verification phantom according to one ormore embodiments of the disclosed subject matter.

FIGS. 7 and 8 are different 3D views of verification phantoms withelements inside phantoms according to one or more embodiments of thedisclosed subject matter.

FIG. 9 is a plan view (coronal plane, anterior-posterior view)illustrating positions of elements within of a verification phantomaccording to one or more embodiments of the disclosed subject matter.

FIG. 10 is a plan view (sagittal plane, left-right view) illustratingpositions of elements within a verification phantom according to one ormore embodiments of the disclosed subject matter.

FIGS. 11 and 12 are plan views (coronal plane, anterior-posterior views)illustrating positions of density inserts within a verification phantomaccording to one or more embodiments of the disclosed subject matter.

FIG. 13 is a top perspective view of a dosimetric insert in an openposition of a verification phantom according to one or more embodimentsof the disclosed subject matter.

FIG. 14 is a perspective view of a verification phantom with adosimetric insert in an open position according to one or moreembodiments of the disclosed subject matter.

FIG. 15 is a plan view (coronal plane, anterior-posterior view) of adosimetric insert in an open position with a film insert according toone or more embodiments of the disclosed subject matter.

FIGS. 16-17 are plan views of film inserts for inserting into testphantoms according to one or more embodiments of the disclosed subjectmatter.

FIG. 18 is a perspective view of a dosimetric insert in an open positionof a verification phantom according to one or more embodiments of thedisclosed subject matter.

FIG. 19 is a plan view (coronal plane, anterior-posterior view)illustrating a film insert in a verification phantom according to one ormore embodiments of the disclosed subject matter.

FIG. 20 is a plan view (sagittal plane, left-right view) of the filminsert of FIG. 19.

FIG. 21 is a screen shot of an optical surface detection software wherethe detected and reference phantom surface is shown together withtranslations and rotations to match both surfaces.

FIG. 22 shows a CT slice showing a central plane of a verificationphantom according to one or more embodiments of the disclosed subjectmatter.

FIG. 23 shows a 3D view with two orthogonal CT planes of a verificationphantom according to one or more embodiments of the disclosed subjectmatter.

FIG. 24 is a kV image of a verification phantom according to one or moreembodiments of the disclosed subject matter.

FIG. 25 is a MV image of a verification phantom according to one or moreembodiments of the disclosed subject matter.

FIG. 26 is a flow chart illustrating a process for performing qualityassurance check on a radiation treatment delivery system using averification phantom according to one or more embodiments of thedisclosed subject matter.

FIG. 27 is a flow chart illustrating a process for performing qualityassurance check on a radiation treatment delivery system using averification phantom according to one or more embodiments of thedisclosed subject matter.

DETAILED DESCRIPTION

Patients undergoing radiation therapy are typically placed on atreatment platform of a radiation treatment gantry. The gantry has aradiation source that is used to generate a radiation beam thatirradiates a region of interest in the patient, such as a diseasedtissue including a tumor or cancerous growth site. When delivering theradiation, a plurality of radiation beams may be directed to the targetarea of interest from several positions outside the body. The gantry canbe rotated to provide the radiation beams from different positions. Thepoint at which beam trajectories converge or intersect is generallyreferred to as the isocenter. The isocenter typically receives thelargest radiation dose because of the cumulative radiation received frommultiple radiation beams. Prior to exposing the patient to the radiationbeams, the patient is positioned in the treatment device so that thelocation of the treatment plan isocenter corresponds with the isocenterof the machine. An integral part of the radiation treatment process isthe coincidence of the treatment plan isocenter with the isocenter ofthe machine. The isocenter coincidence is, however, affected by manyfactors, one of which is the lack of knowledge regarding the preciselocation of the machine isocenter. In existing systems, the isocenter ofa radiation system is identified by a set of fan-beam room lasers, eachof which defines an orthogonal plane. These planes intersect theisocenter to identify that position. Over time, the laser may shift fromtheir original location, which results in a shift of the intersectionpoint. Thus, the intersection point of the laser beams may deviate fromthe true isocenter location. If the lasers are not realigned toprecisely determine the machine isocenter, the coincidence of thetreatment plan isocenter with the isocenter of the machine will beaffected. The isocenter coincidence is also affected in clinicalpractice by the radiation treatment workflow, including imaging, targetalignment that is often software based, and treatment couch motion.

An object of the invention is therefore to provide an end-to-end phantomassembly that can be used to verify the isocenter alignment device; thatmimics clinical radiation treatment workflow and verifies final targetalignment based on imaging with the radiation treatment isocenter; andthat can aid the assessment of the entire clinical radiation treatmentprocess, including computed tomography (CT) performance, such as, butnot limited to, verification of geometric accuracy of the CT data set,placement of the isocenter in the planning systems, transfer ofcoordinates from CT to linear accelerator through the planning system,couch motion, imaging alignment, beam collimation, and coincidence ofthe imaging isocenter with the radiation isocenter.

Another object of the invention is to provide a phantom assembly thatcan be used to execute quality assurance processes to ensure that theradiation treatment delivery system is properly aligned and configuredas specified to accurately deliver a prescribed dose of radiation to thepatient. The phantom assembly can validate that the imaging system, thepositioning system, the treatment couch, and the radiation source areall calibrated and aligned with each other. Moreover, it can verifycoincidence of the imaging isocenter with the radiation isocenter,verify software-based alignments, and verify correct couch and gantryshifts, pitch and roll angles, as well as rotations, based on exactknowledge of the geometry of the phantom.

Another object of the invention is to provide a phantom assembly whichallows simulation of all of the functions of the radiation therapysystem which use X-ray imaging, optical surface imaging, and Calypsoimaging to position the phantom either absolute or relative in space.The phantom can be used to independently verify the phantom or isocenterposition by the use of various positioning systems available on thetreatment device and is able to quantitatively determine a shift betweenthe different isocenter/imaging centers used.

Another object of the invention is to provide a phantom assembly whichfacilitates image based positioning of the phantom using kilovoltage(kV), megavoltage (MV), optical surface, and Calypso monitoring.

Another object of the invention is to provide a phantom assembly whichfacilitates dosimetric analysis of the delivered dose distribution inorder to determine the absolute or relative dose distribution or pointdose values.

FIGS. 1-4 illustrate a universal three-dimensional phantom assembly 100that can fulfill the above described objects. In general, the phantomassembly 100 is a precisely machined phantom (mechanical accuracy < 1/10mm) including an outer housing assembly 130 which can include aplurality of embedded fiducials, markers, and transponders to facilitateimage based positioning and monitoring, as well as an interchangeableinner dosimetric insert 200, positioned within the outer housingassembly 130, which can include one or more dosimetric measuringdevices, to facilitate dosimetric analysis of the delivered dosedistribution. A variety of interchangeable dosimetric inner inserts 200can be used within the outer housing 130 to form the phantom 100.

In an illustrative embodiment, the phantom 100 is a cubic phantom havinga cube shaped outer housing 130 with sides that are approximately 150 mmlong forming a 15×15×15 cm³ outer cube as shown in FIG. 1. The outerhousing 130 can be formed by the assembly of two rectangular housingpieces 110 and 120, as shown in FIG. 2. When assembled together, the tworectangular housing pieces 110 and 120 constitute the outer cube 130.The phantom 100 can include visible cross hair alignment marks 10 on allsix (6) outer faces of the outer housing 130, as well as other fiducialmarkings, such as letter markings 20 (letters F, L, P, for example), asshown in FIGS. 1-10, and discussed in detail below.

To form the outer housing 130, the two housing pieces 110 and 120 areassembled together using connectors, such as, pegs, pins, screws, bolts,rivets, nails, or any other connecting/fastening/locking mechanisms. Inan exemplary embodiment, one of the housing pieces 110 includes two pins111 positioned on a surface 112 of the first housing piece 110 so as toface corresponding holes/cavities 121 located on an opposing surface 122of the second housing piece 120, as shown in FIGS. 2-4. To assemble theouter housing 130, the pins 111 of the first housing piece 110 slideinto the corresponding holes 121 of the second housing piece 120. Thetwo housing pieces 110 and 120 are maintained in an assembled positionby the friction between the pins 111 and the surface of theholes/cavities 121. The pins 111 can be made of a plastic material, suchas, but not limited to, polyvinyl chloride (PVC), and each can have adiameter of about 5 mm. The pins 111 can also be made of a material thatcan simulate bone density. The corresponding holes 121 each have adiameter of approximately 5 mm so as to allow insertion of the pins 111therewithin and assembly and connection of the two housing pieces 110and 120 to each other through friction.

The outer housing 130 including the two housing pieces 110 and 120 canbe formed of a variety of materials that are transparent, or at leasttranslucent, to imaging beams (e.g., X-rays) and are penetrable by theimaging beams. The outer housing 130 can be made of plastic, such as,but not limited to, polyurethane. The outer housing 130 can also be madeof a material that mimics a tissue or organ, such as a material having adensity of 0.45 g/cm³ to mimic/simulate the lung, for example. All edges131 of the outer housing 130 can also be rounded to avoid imagingartifacts, such as CT artifacts. In one embodiment the edges are roundedso as to follow an arcuate path having a 5 degree arc.

Although the illustrated embodiment includes a cubic outer housing 130having particular dimensions and material, it should be appreciated thatouter housing 130 may assume other shapes, materials, or dimensions. Thephantom 100 is also compatible with various stereotactic fixationdevices, such as, but not limited to stereotactic frames and masksystems, and other fixation devices that allow the phantom to be securedto different radiation treatment devices and systems to performend-to-end calibration and verification tests.

FIG. 2 illustrates the cubic phantom assembly 100 in an open positionshowing outer housing 130 in an open form, and the rectangular housingpieces 110 and 120 separated from each other. Each of the housing pieces110, 120 includes a corresponding recess 113, 123 at substantially thecenter location of each of the rectangular housing pieces 110, 120. Whenassembled together, the housing pieces 110 and 120 form a compositerecess within the center portion of the phantom assembly 100. The sizeof the composite recess is such that it can accommodate an innerdosimetric insert 200, having sides approximately 70 mm long, forming a7×7×7 cm³ cubic dosimetric insert 200, as shown in FIGS. 3 and 4. Theinner insert 200 is intended to represent a target region including avolume of interest that represents a tumorous or other lesion within apatient at which the radiation treatment delivery treatment system isdirected to treat with radiation. The purpose of this inner insert 200is to facilitate dosimetric analysis of the delivered dose distribution.The inner insert 200 may be formed of a variety of materials, such as,but not limited to, plastics, including polyurethane. All edges of theinner insert 200 can also be rounded to avoid imaging artifacts. In oneembodiment, the edges are rounded so as to follow an arcuate path havinga 5 degree arc. In embodiments, the inner insert 200 can be made of asoft tissue simulating/mimicking material. In one embodiment, thedensity of the inner insert material is 1.05 g/cm³ to simulate softtissue having the approximate density of water, which is 1.0 g/cm³.Although the illustrated embodiment includes a cubic inner insert 200having particular dimensions and material, it should be appreciated thatthe inner insert 200 may assume other shapes, materials, or dimensions.

The inner insert 200 is positioned within the outer housing 130 so thatthe center 202 of the inner insert 200 corresponds with the center ofthe outer housing assembly 130 and the center of the phantom 100, asshown in FIG. 7. The inner insert 200 can be positioned at the center ofthe outer housing 130 so that the center of the phantom 100 is locatedat the center 202 of the inner insert 200 at the X=0, Y=0, Z=0 positionin an X, Y, Z coordinate system.

The phantom 100 can also include visible cross-hair alignment markings10 on all six (6) outer faces of the outer housing 130, as well as otherfiducial markings, such as letter markings 20 (letters F, L, P, forexample), and line markings 20′ as shown in FIGS. 1, 5, and 6. FIG. 5illustrates a top view of the phantom 100 including the cross-hairalignment markings 10, line markings 20′, and the letter markings 20etched into the outer housing 130 of the phantom 100. Thecross-alignment markings 10 can have a depth of about 1 mm and a widthof about 1 mm, and can be precisely positioned on the outer surface ofthe phantom 100 so as to intersect in the middle of each of itsrespective six outer surfaces. FIG. 5 also illustrates letter markings Fand L etched into an upper surface of the housing piece 110. The depthsof the etchings are about 3 mm. Each of the letters is approximately 10mm long and is precisely positioned relative to the center of thephantom 100. The letter F is positioned such that the middle point alongthe length of the letter F is positioned at (X=50 mm, Y=−75 mm, Z=−62mm) from the center location (X=0, Y=0, Z=0) of the phantom 100. Theletter L is positioned such that the middle point along the length ofthe letter L is positioned at (X=62 mm, Y=−75 mm, Z=30 mm) from thecenter location (X=0, Y=0, Z=0) of the phantom 100.

FIG. 6 illustrates a side view of the phantom 130, with the letters Pand F etched into a side surface of the bottom housing piece 120 of theouter housing 130. Each of the letters is approximately 10 mm long andis precisely positioned relative to the center of the phantom 100. Theletter P is positioned such that the middle point along the length ofthe letter P is positioned at (X=75 mm, Y=62 mm, Z=50 mm) from thecenter location (X=0, Y=0, Z=0) of the phantom 100. The letter F ispositioned such that the middle point along the length of the letter Fis positioned at (X=75 mm, Y=−30 mm, Z=−65 mm) from the center location(X=0, Y=0, Z=0) of the phantom 100. One or more additional letters canbe positioned on the surface of the outer housing 130.

The letter markings can be made of a material such as aluminum having adensity of about 2.70 g/cm³, for example. Any other metal besidesaluminum, such as copper, for example, can be used for the lettermarkings. The number and material for the lettering, however, is onlyillustrative and any fewer or more letter markings can be used.

Other geometric configurations could be substituted for the lettermarkings. The line-marking 20′, cross-hair markings 10, the lettermarkings 20, and/or the geometric configurations can be used forprecision setup of the housing 130, the inner dosimetric insert 200, aswell as the phantom 100 in the treatment and/or calibration devices.Each of these letter markings and/or geometric configurations can alsobe used to verify the capacity of the software used for automaticcontouring operations for organs of different densities during targetvolume reconstruction.

The cubic outer housing 130 can also be embedded and/or impregnated withtracking fiducials such as markers and transponders. Markers in thephantom 100 can be used to determine geometric parameters for theradiation treatment system. Geometric parameters refer to variablesassociated with an operation of the system, such as, but not limited to,a position component of the system, distance between two components ofthe system, a source-to-imager distance (SID), a source-to-axis distance(SAD), an axis of rotation, a center of rotation, a piercing point, anisocenter, or the like. The various geometric parameters can be used indifferent applications. For example, SID and SAD and piercing pointinformation can be used as parameters for cone-beam CT reconstructions,the rotation center can be used to calibrate alignment lasers associatedwith the system, and/or to corroborate alignment of dual-plane imagingsystems, and/or to verify shifts and rotations of the gantry and/ortreatment couch.

The transponders, such as electromagnetic transponders, in the phantom100 can be used to communicate with an electromagnetic navigationalsystem, such as, but not limited to, a Calypso localization systems,using radiofrequency waves. A Calypso system is an electromagnetic,transponder-based, target localization and monitoring system, includingan electromagnetic array which contains an energy source that can excitethe transponders and receivers that detect each transponder's frequencyto determine its location coordinates. Each of the transponderstransmits a unique non-ionizing radiofrequency signal to the array,generating position and motion information about the target in which itis imbedded. The transponder's location is subsequently correlated tothe treatment or machine isocenter through optical reflectors on thedetector. A user interface can display the positional information bothinside and outside of the treatment room. The system can also bemultiplexed so that multiple transponders tuned at different frequenciescan be discretely detected. The electromagnetic transponders and theCalypso system can also provide target localization and monitoringduring radiation treatment delivery. During radiation treatment, thetransponders and the Calypso system can provide the cliniciancontinuous, real-time monitoring of the target and can alert theclinician when the target is outside of acceptable boundaries due toorgan motion, thereby enabling corrections during the treatmentdelivery.

In an illustrative embodiment, sixteen markers 140-156 arc regularlydistributed throughout the cubic outer housing 130, as shown in FIGS. 7and 8. Each of the markers can be a radio-opaque marker, such as aceramic BB (sphere) having a 5 mm diameter cross-section. Inembodiments, the ceramic BB sphere markers 140-156 can be made of Al₂O₃.The BB sphere markers 140-155 can be distributed within the housing 130so that twelve (12) of the markers are embedded within one of thehousing pieces 110, 120, and the remaining four (4) of the BB markersare embedded within the other housing piece. One way to embed themarkers into the outer housing 130 is by machining inserts withpositioning grooves precisely matching the dimensions of the markers.However, other embedding/impregnating methods may be used. Six of the BBmarkers 140-145 are embedded in the upper surface 122 of the housingpiece 120 so as to be positioned along two opposing upper edges (sides)of housing piece 120, with three markers 140-142 located along one ofthe edges and three markers 143-145 along the opposing edge, eachapproximately 10 mm from the edges of the housing piece 120. The centerof each of the markers 140-145 is positioned approximately 65 mm fromthe center of the phantom 100 along the X axis, with marker 140 locatedat (X=65 mm, Y=5 mm, Z=−65 mm), marker 141 located at (X=65 mm, Y=5 mm,Z=0 mm), marker 142 located at (X=65 mm, Y=5 mm, Z=65 mm), marker 143located at (X=−65 mm, Y=5 mm, Z=65 mm), marker 144 located at (X=−65 mm,Y=5 mm, Z=0 mm) and marker 145 located at (X=−65 mm, Y=5 mm, Z=65 mm).

Two BB sphere markers 146-147 are embedded in the upper surface 122 ofthe housing piece 120 approximately 40 mm from the center of the phantom100 along the X axis and approximately 40 mm from the center of thephantom 100 along the Y axis, at locations which are adjacent todiagonally opposing corners of the recess 123 of the housing piece 120,with the center of marker 146 located at (X=−40 mm, Y=5 mm, Z=−40 mm)and the center of marker 147 located at (X=40 mm, Y=5 mm, Z=40 mm).Three BB sphere markers 148-150 can be embedded within a middle portionof the bottom surface of the housing piece 120, approximately 10 mm fromthe bottom of the housing piece 120, with the center of marker 148located at (X=0 mm, Y=+65 mm, Z=−65 mm), the center of marker 149located at (X=0 mm, Y=65 mm, Z=0 mm), and the center of marker 150located at (X=0 mm, Y=65 mm, Z=65 mm). The twelfth marker 151 is alsoembedded in housing piece 120 at (X=0 mm, Y=−40 mm, Z=−40 mm).

The remaining four BB sphere markers 152-155 can be embedded within thehousing piece 110, such that three BB sphere markers 152-154 areembedded within a middle portion of the upper surface of the housingpiece 120, approximately 10 mm from the upper edge of the housing piece110, forming a mirror image of the three BB sphere markers 148-150embedded in the housing piece 120, with the center of marker 152 locatedat (X=0, Y=−65 mm, Z=−65 mm), the center of marker 153 located at (X=0mm, Y=−65 mm, Z=0 mm), and the center of marker 154 located at (X=0 mm,Y=−65 mm, Z=65 mm). The sixteenth marker 155 is also embedded in housingpiece 120 at (X=0 mm, Y=−40 mm, Z=40 mm) so as to diagonally opposemarker 151.

The illustrated embodiment includes a total of sixteen (16) markers140-155. However, the phantom 100 can have fewer or more than sixteenmarkers. Also, in the illustrated embodiment, the markers 140-156 arepositioned relative to each other such that they collectively form aregular pattern. However, in other embodiments, the markers 140-155 canbe positioned such that the markers collectively form an irregularpattern. Also, instead of embedding the markers 140-156 into the wallsof the outer housing 130, the markers 140 can be secured permanently ordetachably to interior surfaces of the outer housing 130 using securingmechanism, such as, Velcro, pins, clamps, screws, bolts, clips, or thelike. In an alternative embodiment, the markers 140-155 can be otherthan radio-opaque markers and can have cross-sections that are between2-5 mm, or any other cross-sections.

The phantom 100 can also include three electromagnetic transponders160-162 embedded into the outer housing 130 at precise locations asillustrated in FIGS. 7 and 8. One way to embed the transponders into theouter housing 130 is by machining inserts with positioning groovesprecisely matching the dimensions of the transponders. However, othermethods may also be used to embed the transponders into the outerhousing 130 of phantom 100. Each of the electromagnetic transponders canbe made of a material including glass housing with a ferrite core andeach can be approximately 9 mm long and has a 2 mm cross-section. Eachof the transponders can transmit a unique non-ionizing radiofrequencysignal.

A first (apex) transponder 160 is positioned approximately 45 mm fromthe center (X=0, Y=0, Y=0) of the phantom 100, with the center of thetransponder located at (X=0 mm, Y=0 mm, Z=−45 mm), a second (left base)transponder 161 is positioned approximately 45 mm from the center of thephantom 100, with the center of the second transponder located at (X=45mm, Y=0 mm, Z=−5 mm), and a third (right base) transponder 162 ispositioned approximately 45 mm from the center of the phantom 100, withthe center of the third transponder located at (X=−45 mm, Y=0 mm, Z=5mm). The first transponder 160 is positioned so that its length extendsalong the X axis, the second transponder 161 is positioned so that itslength extends along the Y axis, and the third responder 162 ispositioned so that its length extends along the Z axis.

The illustrated embodiment includes a total of three (3) transponders160-162, with the first transponder 160 being responsive to a 300 kHzfrequency, the second transponder 161 being responsive to a 400 kHzfrequency, and the third transponder 162 being responsive to a 500 kHzfrequency. The transponders 160-162 can be Beacon electromagnetictransponders that are configured to communicate with a Calypsolocalization system using radiofrequency waves for target localizationand monitoring. The phantom 100, however, can have fewer or more thanthree transponders, and different frequencies. In the illustratedembodiment, the transponders arc positioned relative to each other suchthat they collectively form a regular pattern. However, in otherembodiments, the transponders can be positioned such that thetransponders collectively form an irregular pattern.

The exemplary locations and dimensions of the different elements(markings, transponders, pins, etc.) embedded in the phantom 100 arefurther illustrated in FIG. 9, which is a plan view of the phantom in acoronal plane (anterior-posterior view, isocenter plane: Y=0), and inFIG. 10, which is a plan view of the phantom 100 in a sagittal plane(left-right view, isocenter plane: X=0).

The phantom 100 can further include one or more density inserts 171-173embedded within the outer housing 130 at specific locations. Thesedensity inserts 171-173 can have specific geometries and differentdensities and can represent different densities of different organs andmedia of the human body, which the radiation beam of the radiationtreatment device may pass through. Density inserts are helpful toimprove the accuracy of the image matching algorithms and to generate aspectrum of different grey values in the images to more closely reflectthe one in patients.

Density inserts 170-173 each can have a cubic shape with sides 15 mmlong, for example. Two density inserts 170 and 171 can be embedded inthe lower housing piece 120 so as to be positioned at diagonallyopposing corners of the housing piece 120, with element 170 having itscenter located at (X=52.5 mm, Y=+52.5 mm, Z=−52.5 mm) and element 171having it center located at (X=−52.5 mm, Y=52.5 mm, Z=+52.5 mm) from thecenter of the phantom 100. The other two density inserts 172-173 can beembedded in the upper housing piece 110 so as to be positioned atdiagonally opposing corners of the housing piece 110, with element 172having its center located at (X=52.5 mm, Y=−52.5 mm, Z=52.5 mm) andelement 173 having it center located at (X=−52.5 mm, Y=−52.5 mm, Z=−52.5mm) from the center of the phantom, as shown in FIGS. 7 and 8. FIG. 11is a planar view of the phantom with density inserts 170, 172 in acoronal plane (anterior-posterior view), and FIG. 12 is a planar view ofdensity inserts 171, 173 in the coronal plane (anterior-posterior view).

Density inserts 170 and 172 can be formed of materials that mimic bonedensity and density inserts 171 and 173 can be made of materials thatmimic lung density. The bone simulating inserts can be made of PVC andcan have a density of 1.42 g/cm³ and the lung simulating inserts can bemade of polyurethane and can have a density of 0.25 g/cm³, for example.Any other materials and/or combination of density inserts with differentmaterials, however, can be used. Also, the illustrated embodimentincludes a total of four (4) density inserts 170-173. However, thephantom 100 can have fewer or more than four density inserts.

In the illustrated embodiment, the density inserts 170-173 arepositioned relative to each other such that they collectively form aregular pattern. However, in other embodiments, the density inserts170-173 can be positioned such that the inserts collectively form anirregular pattern. Also, instead of embedding the density inserts170-173 into the walls of the outer housing 130, the inserts 170-173 canbe secured permanently or detachably to interior surfaces of the outerhousing 130 using securing mechanism, such as, Velcro, pins, clamps,screws, bolts, clips, or the like. In an alternative embodiment, thedensity inserts 170-173 can be formed of other than the illustrativetissue or organ simulating materials and can have other cross-sections.

In an illustrative embodiment, the dosimetic inner insert 200 includestwo separate rectangular insert pieces 210 and 220, which when assembledtogether form the inner cubic insert 200, as shown in FIGS. 2-4. Theinner cubic insert 200 can be positioned inside the composite recesswithin the outer housing 130 so as to nest within the composite recesswhen the two housing pieces 110, 120 are assembled together. When thehousing 130 is assembled together, the first insert piece 210 rests inthe recess 113 of the first housing piece 110 and the second insertpiece 220 rests in the recess 123 of the second housing piece 120. Theinsert pieces 210 and 220 can be formed of a material such aspolyurethane having a density of 1.05 g/cm³, for example, which cansimulate a soft tissue. However, the insert pieces 210 and 220 can alsobe made of any other materials having different densities which canrepresent different densities of different organs and media of the humanbody through which the radiation beam of the radiation treatment systemmay pass.

FIGS. 2 and 13 illustrate a first embodiment of the two insert pieces210 and 220 in an opened position. FIG. 14 illustrates a secondembodiment of the two insert pieces 210 and 220, with FIG. 14 alsoshowing a dosimeter film insert 201 positioned on the upper surface ofinsert piece 220, so that when the two insert pieces 210 and 220 areassembled together, the film insert 201 rests there-between. Thedosimeter film insert 201 can be used to determine the dose distributionor point dose value that the target/phantom is exposed to.

In an exemplary embodiment, one of the insert pieces 210 includes twopins 211 and two holes 212 positioned on surface 203 of the insert piece210 so as to face corresponding holes 222 and pins 221 positioned on anopposing surface 204 of the second insert piece 220. The pins 211 and221 can be attached to or secured to their respective insert pieces 210,220 using any fastening or bonding mechanism, such as, but not limitedto, nails, screws, etc. In one embodiment, the pins 211, 221 are gluedto the insert pieces 210, 220 using an adhesive. To assemble the innerinsert 200, the pins 211 of the first insert piece 210 can slide intothe holes 222 of the second insert piece 220, and pins 221 of the secondinsert piece 220 can slide into the holes 212 of the first insert piece210. The two insert pieces 210 and 220 are maintained in an assembledposition by the friction between the pins 211, 221 and the surface ofthe holes 212, 222. The pins 211, 221 can be made of a plastic material,such as, but not limited to, polyvinyl chloride (PVC), and each can havea diameter of about 3 mm and a length of about 20 mm. The pins 211, 221can also be made of a material that simulates the density of a tissue ora body organ, such as, but not limited to bone density. Thecorresponding holes 212, 222 also have a diameter of approximately 3 mmand a length of about 20 mm so as to allow insertion of the pins 211,221 there-within and the assembly and connection of the two insertpieces 210 and 220 to each other through friction.

FIG. 15 is a top view of an illustrative film insert 201 that can beused with the insert pieces 210, 220 shown in FIG. 14. FIG. 15 isshowing dimensions and precise positions of the pins 221, holes 222, andfilm insert 201 for an exemplary embodiment. The film insert 201receiving surface of the insert piece 210 is identical, except for thepositions of the pins 211 and holes 212 on the surface 203. Each of thepins 221 can be positioned at approximately 5 mm from the corner edgesof the insert piece 220, so that the center of the pin 221 located inthe right corner of the insert piece 220 is positioned at (X=35 mm, Y=0mm, Z=−30 mm) and the center of the insert pin 221 located in thediagonally opposed corner is positioned at (X=−35 mm, Y=0 mm, Z=30 mm)from the center of the phantom located at (X=0, Y=0, Z=0). The holes 222are positioned similarly as the pins 221 in the remaining two corners ofthe insert piece 220. The pins 211 and holes 212 of the insert piece 210are similarly located as the corresponding holes 222 and pins 221 on theinsert piece 220. The locations, dimensions, and number of pins areexemplary, and any other locations, dimensions, and number of pins, maybe used in order to fit the insert pieces 210, 220. The film insert 201can be positioned in between the insert pieces 210, 220 using pins 211,221. Alignment holes 202, 213, 223 can also be used to mark the film sothat these markings are later seen in CT images used for dose planning,for example. The alignment hole markings form known points on the filmplane, which helps to later align the film to the planning isocenter todetermine the shift between measured dosimetric isocenter and planneddosimetric isocenter. In an exemplary embodiment, four alignment holes223 are made in the insert piece 220, each positioned at a respectivecorner portion of the insert piece 220, so that the centers of thealignment holes 223 are each positioned approximately 15 mm from therespective edges of the insert piece 220, at the following locationsrelative to the center of the phantom: hole 1 at (X=20 mm, Y=0 mm, Z=−20mm), hole 2 at (X=−20 mm, Y=0 mm, Z=−20 mm), hole 3 at (X=20 mm, Y=0 mm,Z=20 mm), and hole 4 at (X=−20 mm, Y=0 mm, Z=20 mm). The alignment hole202 is positioned at (X=0, Y=0, Z=0). The holes 213 and 202 in theinsert piece 210 are located at identical locations as in the insertpiece 220. The locations, dimensions, and number of holes are exemplary,and any other locations, dimensions, and number of holes, may be used.

For better alignment and visualization of the film insert 201 relativeto other elements of the insert piece 200 and the phantom 100, thealignment holes 202, 213, 223 can also include pins/pegs or any othermechanisms that can be inserted into one or more of the alignment holes202, 213, 223 of one or both of the insert pieces 210, 220. In anembodiment, pins or pegs having 1 mm cross-sections and lengths of about5 mm can be inserted into the alignment holes 202, 213, 223 so as to beflush with surfaces 203 and 204. The pins can be made of a plasticmaterial that simulates a tissue or an organ of the body, such as, butnot limited to the lung. When the insert pieces 210 and 220 are securedto each other through pins 211, 221, the dosimeter film insert 201 issecurely positioned and aligned relative to the insert pieces 210, 220and relative to the inner cubic insert 200. The insert piece surfaces203 and 204 can also be slightly recessed so as to accommodate the filminsert flush therebetween.

In some embodiments, the dosimetic insert 200 can also hold a centrallylocated marker, such as a steel or tungsten BB sphere marker in order toincrease the contrast in MV/kV images. The film insert 201 can be asquare film insert having a length of 56 mm on each side and a 0.3 mmthickness. To accommodate such a film insert 201 flush in between thetwo insert pieces 210, 220, the depth of each of the surface 203, 204recesses is made to be about 0.15 mm. The films insert 201 can includeany type of radiochromic films, including standard and/orhigh-sensitivity radiochromic films.

FIG. 16 shows an illustrative film insert 205 that can be used with theinsert pieces 210, 220 shown in FIG. 13. The film insert 205 can have 66mm long sides. The edges of the film insert 205 can be rounded to followan arc having radius of about 2 mm to eliminate imaging artifacts. Filminsert 205 can also include four circular cutouts 215 positioned at thefour corners of the film insert 205. These cutouts 215 allow the pins211 to hold and position the film insert 205 within the inner insert200. Each of the circular cutouts 215 has a diameter of about 3 mm andis positioned so that its center is located approximately 3.5 mm fromthe edges of the film insert 205. The distance between adjacent circularcutouts is approximately 59 mm. The film insert 205 can also includeother fiducial markers, such as an equilateral triangle-shaped cutout216 having 3 mm long sides made along one of the sides of the filminsert 205, as well as a plurality of square-shaped cutouts 217 having 3mm sides made along another side of the film insert 205 to uniquelyidentify the film plane after the phantom 100 has been dismantled. Thetriangular cutout 216 can be positioned about 12 mm from the edge of thefilm insert 205 and two of the square-shaped cutouts 217 can each bepositioned about 12 mm from corresponding edges of the film insert 205at about 42 mm from each other. The films insert 205 can include anytype of radiochromic films, including standard and/or high-sensitivityradiochromic films.

The dimensions and precise positions of the pins 221, holes 222, andfilm insert 205 is slightly different than the dimensions and positionsof the film insert 201 in the insert piece 220 of the first embodiment.Each of the pins 221 can be positioned at diagonally opposed corners ofthe insert piece at approximately 4 mm from the corner edges of theinsert piece 220. The holes 222 are positioned similarly as the pins 221in the remaining two corners of the insert piece 220. The pins 211 andholes 212 of the insert piece 210 are similarly located as thecorresponding holes 222 and pins 221 on the insert piece 220. Thelocations, dimensions, and number of pins arc exemplary, and any otherlocations, dimensions, and number of pins, may be used in order to fitthe insert pieces 210, 220.

The film insert 205 can be positioned in between the insert pieces 210,220 using pins 211, 221. Alignment holes 202, 213, 223 can also be usedto mark the film so that these markings are later seen in CT images usedfor dose planning, for example. The alignment hole markings form knownpoints on the film plane, which helps to later align the film to theplanning isocenter to determine the shift between measured dosimetricisocenter and planned dosimetric isocenter. In an exemplary embodiment,four alignment holes 223 are made in the insert piece 220, eachpositioned at a respective corner portion of the insert piece 220, sothat the centers of the alignment holes 223 are each positionedapproximately 9 mm from the respective edges of the insert piece 220.The holes 213 and 202 in the insert piece 210 are located at identicallocations as in the insert piece 220. The locations, dimensions, andnumber of holes are exemplary, and any other locations, dimensions, andnumber of holes, may be used.

For better alignment and visualization of the film inserts 205 relativeto other elements of the insert piece 200 and the phantom 100, thealignment holes 202, 213, 223 can also include pins/pegs or any othermechanisms that can be inserted into one or more of the alignment holes202, 213, 223 of one or both of the insert pieces 210, 220. In anembodiment, pins or pegs having 1 mm cross-sections and lengths of about5 mm can be inserted into the alignment holes 202, 213, 223 so as to beflush with surfaces 203 and 204. The pins can be made of a plasticmaterial that simulates a tissue or an organ of the body, such as, butnot limited to the lung. When the insert pieces 210 and 220 are securedto each other through pins 211, 221, the dosimeter film insert 205 issecurely positioned and aligned relative to the insert pieces 210, 220and relative to the inner cubic insert 200. The insert piece surfaces203 and 204 can also be slightly recessed so as to accommodate the filminsert flush therebetween.

The film insert 205 can be a square film insert having a length of 66 mmeach side and a 0.3 mm thickness. To accommodate such a film insert 205flush in between the two insert pieces 210, 220, the depth of each ofthe surface 203, 204 recesses is made to be about 0.15 mm. The filmsinsert 205 can include any type of radiochromic films, includingstandard and/or high-sensitivity radiochromic films.

FIG. 17 illustrates another film insert 206 that can be used with theinsert pieces 210, 220 of FIG. 13. The film inserts 206 can have sides66 mm long. The edges of the film inserts 206 can be rounded to followan arc having radius of about 2 mm to eliminate imaging artifacts. Filminserts 206 can also include four circular cutouts 215 positioned at thefour corners of the film insert 206. These cutouts 215 hold and positionthe film insert within the inner insert 200 via the pins 211, 221. Eachof the circular cutouts 215 has a diameter of about 3 mm and ispositioned so that its center is located approximately 3.5 mm from theedges of the film insert 206. The distance between adjacent circularcutouts is approximately 59 mm. The film insert 206 can also includeother fiducial markers, such as an equilateral triangle-shaped cutout216 having 3 mm long sides made along one of the sides of the filminsert 206, as well as a plurality of square-shaped cutouts 217 having 3mm sides made along another side of the film insert 206 to identifyuniquely the film plane after the phantom 100 has been dismantled. Thetriangular cutout 216 can be positioned about 12 mm from the edge of thefilm insert 206 and two of the square-shaped cutouts 217 can each bepositioned about 12 mm from corresponding edges of the film inserts 206at about 42 mm from each other. Each of the film inserts 206 can alsoinclude an elongated rod-shaped geometric cutout 218 having a diameterof about 2 mm and a length of about 33 mm. The rod-shaped cutout 218 canbe made in a different side of the film insert 206 than where thetriangular 216 and cubic cutouts 215 are made, so that its lengthextends along an axis which is perpendicular to the side of the filminsert 206 where the square-shaped cutouts 217 are made. The rod-shapedcutout 218 extends about 33 mm from the side in which the triangularcutout 216 is made.

The number, shape, size, and positions of the geometric configurationsin either of these films are only illustrative and any fewer or moregeometric configurations, and different shapes, positions and sizes canbe used. These geometric markings can be positioned to provide areference position to the dosimeter film inserts held in the phantom 100by the cubic insert 200. These geometric markings can be used to definea reference location and/or coordinate system so that the location ofother features developed on the dosimeter films may be determined withrespect to the radiation treatment device. When the phantom 100 isirradiated from a plurality of external radiation beam source positions,the radiation beams from the different positions provide image features(such as lines, or other marks) to the dosimeter films, which can beused to determine the trajectory of the respective radiation beams.These trajectories can then be used to determine an isocenter of theradiation treatment system in a coordinate system defined by thereference marks formed in the image. Additionally, the resultant dosedistribution planned and irradiated can be used to determine theisocenter shift of the planned with respect to the measured 2D doesdistribution of the film.

In an alternative embodiment, the inner cubic assembly insert 200includes four separate rectangular insert pieces 310, 320, 330, and 340which when assembled together form the inner cubic insert 200, as shownin FIG. 18. The inner insert 200 can be positioned inside the compositerecess so as to nest within the composite recess when the two housingpieces 110, 120 are assembled together to form phantom 100′ shown inFIG. 8. When the outer housing 130 is assembled together, the first andsecond insert pieces 310, 320 rest in the recess 113 of the firsthousing piece 110 and the third and fourth insert pieces 330, 340 restin the recess 123 of the second housing piece 120. The insert pieces310, 320, 330, and 340 can be formed of a material such as polyurethanehaving a density of 1.05 g/cm³, for example. However, the insert pieces310, 320, 330, and 340 can be made of any other material havingdifferent densities which can represent different densities of differentorgans and media of the human body which the radiation beam of theradiation treatment device may pass through.

FIG. 18 illustrates the four insert pieces 310, 320, 330, 340 in anopened position. In one embodiment, two (2) film inserts can bepositioned between the four insert pieces 310, 320, 303, and 340 beforeassembling the pieces 310, 320, 330, and 340 together, so that, whenassembled, the combined film inserts rest between the assembled insertpieces 310, 320, 330, 340 in two orthogonal planes. The two film insertswill rest in the inner cubic insert 200 and the phantom 100′ as shown inFIG. 8. The first and second film inserts can be film inserts as shownin FIG. 17. When two crossed-film inserts 206 are used in the innerinsert 200, the rod-shaped cutouts 218 in each film insert 206 interlockwith each other to form a crossed-film insert by sliding one film insertinto the rod-shaped cutout of the other film insert. The first andsecond film inserts 206 can slide into each other (i.e., mate with eachother) via their respective rod-shaped cutouts. When the two filminserts are mated with each other via their respective rod-shapedcutouts, the two film inserts are interlocked to form a dual-crossedfilm insert, with the first film insert resting in a plane which isperpendicular to a plane in which the second film insert rests. The twofilm inserts are positioned so as to slice through the center of theinner insert 200 in orthogonal planes. Since the film inserts slicethrough two-dimensional planes within the insert 200, the delivered doseimage developed thereon will capture two-dimensional slices of theactual dose delivered. Thus, treatment planning software can also beused to determine calculated doses that should be delivered along theseplanes. The film inserts 206 can include any type of radiochromic films,including standard and/or high-sensitivity radiochromic films.

The first and second insert pieces 310 and 320 each include pins 315 andholes 316 positioned on their inner surfaces which face each other andthe other two inserts 330, 340, so that the first and second insertpieces 310 and 320 can be assembled to each other, as well as to insertpieces 330, 340 through the pins connected/attached to their respectiveinner surfaces. In the exemplary embodiment pins can be used to securelyassemble the insert pieces to each other by friction between the pinsand the surfaces of the corresponding holes. The pins 315 can be made ofa plastic material, such as, but not limited to, polyvinyl chloride(PVC), and each can have a diameter of about 3 mm and a length of about20 mm. The pins 315 can also be made of materials that simulate bonedensity. The pins 315 can be securely attached to their correspondinginsert pieces by gluing the pins onto the insert piece surfaces, forexample. However, other securing/connecting/attaching methods may alsobe used. The corresponding holes can also have a diameter ofapproximately 3 mm and a length of about 5 mm so as to allow insertionof the pins therewithin and assembly and connection of the four insertpieces 310, 320, 330 and 340 to each other through friction.

When the insert pieces 310, 320, 330, and 340 are assembled, the dualcrossed film inserts are securely positioned and aligned relative to theinner insert 200. The film inserts are precisely cut to fit into theinsert 200 so that the positions of the film inserts within the insert200 are precisely known. The insert piece surfaces can also be slightlyrecessed so as to accommodate the film inserts flush therebetween. Dueto the precise positioning of the dosimeter dual-crossed film insertswithin the cubic inner insert 200 and within the phantom 100′, accuratethree-dimensional translational and rotational alignment validation canbe provided.

In an alternative embodiment, the inner insert 200 can be formed ofthree different insert pieces with one insert piece (i.e., first insertpiece) including a slit having a specific width across substantially amiddle portion thereof so as to allow insertion of a portion of a firstfilm insert therein. When inserted in the slit, the portion of the filminsert is resting within the first insert piece and the rest of the filminsert is resting outside of the first insert piece in a plane which isorthogonal to the surface of the first insert piece. A second filminsert can be positioned on the upper surface of the first insert piece,so that the first and second film inserts form a dual crossed filminsert when the insert pieces are assembled. The other two insert pieces(second and third) are positioned on the first insert piece so as tohold the first film insert there-between.

In an exemplary embodiment, the first and the second film inserts arefilm inserts as shown in FIG. 17.

In another embodiment, the first film insert can be a film insert asshown in FIG. 16 and the second film insert is made up of two filminsert pieces, located on either side of the slit in the first insertpiece. FIGS. 19 and 20 illustrate top views of the second film insertpieces. The film insert pieces each can have a side 28 cm long andanother side which is 56 mm long, respectively, so as to leave aslit/cut having a width of 0.3 mm where the two film insert pieces meet.The film insert pieces can be positioned on the insert piece usingalignment holes 321. In an exemplary embodiment, four alignment holes321 arc made in the insert piece, each positioned at a respective cornerportion of the insert piece, so that the centers of the alignment holes321 are each positioned approximately 15 mm from the respective edges ofthe insert piece 310, at the following locations relative to the centerof the phantom 100: hole 1 at (X=−20 mm, Y=0 mm, Z=−20 mm), hole 2 at(X=−20 mm, Y=0 mm, Z=20 mm), hole 3 at (X=20 mm, Y=0 mm, Z=−20 mm), hole4 at (X=20 mm, Y=0 mm, Z=20 mm).

For better alignment and visualization of the film inserts relative toother elements of the insert piece 200 and the phantom 100, thealignment holes 321 can also include pins/pegs or any other mechanismsthat can be inserted into one or more of the alignment holes 321 of theinsert piece. In an embodiment, pins or pegs having 1 mm cross-sectionsand lengths of about 5 mm can be inserted into the alignment holes 321so as to be flush with the insert piece. The pins can be made of aplastic material that simulates a tissue or an organ of the body, suchas, but not limited to the lung.

When the insert pieces are assembled, the dosimeter film inserts aresecurely positioned and aligned relative to the insert pieces andrelative to the inner cubic insert 200 to form a dual crossed filminsert. Due to the precise positioning of the dosimeter film insertswithin the cubic inner insert 200 and within the phantom 100′, accuratethree-dimensional translational and rotational alignment validation canbe provided.

In an alternative embodiment, the cubic insert 200 can be made of onesingle piece and can include a plurality of groves, each being able toaccommodate a respective film insert, such that when the film insertsare inserted into the respective groves, the plurality of film insertsare positioned in a stacked configuration. The cubic insert 200 canfurther include additional fiducial markers so that the position of eachfilm relative to the cubic insert 200 is precisely known.Three-dimensional (3D) dosimetry can be achieved with the phantomincluding such a cubic insert 200. In another embodiment, the stack offilms in the cubic insert 200 is stacked in such a way as to achieve a2½D dosimetry.

Instead of, or in combination with the film inserts, the cubic insert200 can also include thermoluminescent dosimeters (TLD) for dosedistribution measurements. In this case, instead of, or in combinationwith reading the optical density (blackness) of the film inserts, theamount of light released versus the heating of the individual pieces ofthermoluminescent material can also be measured. The “glow curve”produced by this process is then related to the radiation exposure. Thepoint dose measurement is determined based on this glow curve.

Alternatively, instead of, or in combination with the film inserts, thecubic insert 200 can also include optically stimulated luminescence(OSL) dosimeter films for dose distribution measurements. In this case,instead of, or in combination with reading the optical density(blackness) of the film inserts, photons are detected using aphotomultiplier tube. The signal from the tube is then used to calculatethe dose that the material had absorbed.

Alternatively, instead of or in combination with using the film inserts,the cubic insert 200 can host a dosimetry gel container for 3D dosedistribution measurements.

By precisely positioning dosimetric film inserts, such as, gel, film,TLD and/or OSL dosimeters in multiple planes in the interchangeablecubic insert 200, three-dimensional (3D) imaging of radiation dosedistribution can be achieved, which then allows determining the absoluteor relative dose distribution or point distribution dose values. Knowingthe absolute or relative dose distribution or point distribution dosevalues allows determining the center of the dose distribution or dosevolume/area parameters to be compared to the calculated absolute orrelative dose distribution.

In order to determine dose distribution using the phantom 100, 100′ withthe dosimeter film inserts, an imaging method may be used wherein theradiation source (e.g., X-ray source) of the radiation treatment systememits radiation beams onto the phantom 100, 100′. Subsequently, theradiation source is moved to one or more positions to take aim at theinner insert 200 of the phantom 100, 100′. From each position, theradiation source emits a radiation beam along a trajectory passingthrough the inner insert 200 and impinging upon the dosimeter filminserts to deliver prescribed doses of radiation per the treatment plan.In response to the radiation beams, the dosimeter film inserts areexposed and an exposure image or delivered dose image is developed onthe dosimeter film inserts. The insert 200 can then be removed from thephantom 100, 100′ opened, and the dosimeter film inserts removed foranalyzing. By analyzing the shape, size, position, and/or opticaldensity (amount of exposure represented by the shading on the film) ofthe exposure images on the dosimeter film inserts, alignment and/orcalibration of the radiation source can be validated or amisalignment/invalid calibration exposed.

It will be appreciated that the phantom described herein can measurerelative and absolute dose distribution due to its combination ofvarious dosimeters in a single dosimetric insert. It will also beappreciated that the phantom described herein provides nearly identicalmarker (BB sphere) contrast in kV and MV projection images due to theoptimized material composition of the markers (BB spheres) within thephantom, which allows artifact free CT and CBCT imaging of the embeddedmarkers (BB spheres).

It will further be appreciated that because a variety of materials withdifferent densities are used the phantom described herein, intensityvariations result within X-ray, CT, CBCT, DTS images used in manual andautomatic image registration algorithms, and therefore, the phantom canbe used for the verification of the gantry and collimator rotationangle, jaw and MLC based field size, as well as for treatment couchshifts and rotations, for example.

By emitting multiple radiation beams from different positions onto thephantom 100, 100′, multi-dimensional alignment validation can also beachieved, such as, but not limited to, three-dimensional translationalalignment validation, and three-dimensional translational and rotationalalignment validation (roll, pitch, yaw), which includes validating theability of the radiation treatment system and the patient positioningsystem to achieve accurate translational/rotational placement of thephantom 100, 100′ at the preset position and the ability of theradiation source to arrive at its translational/rotational presetposition.

The reference indicia, fiducial markers, and/or any other marks, such asthe geometric marks on the film and the housing, and the cross-shapedhairline marks, precisely positioned in or on the phantom 100, 100′provide a reference position to the dosimeter film inserts held in thephantom 100, 100′ by the cubic insert 200. These marks being provided bymaterials or coatings that can generate an optically or electronicallydetectable image on the film inserts will generate such detectableimages on the film inserts when exposed to the radiation beams. When thephantom 100, 100′ with the inner insert 200 is irradiated with theradiation beam, these markers generate different patterns on the filminserts. The patterns may be visible after the film inserts aredeveloped to create a digitized image. These marks can be used to definea reference location and/or coordinate system so that the location ofother features developed on the dosimeter films may be determined withrespect to the radiation treatment device. When the phantom 100, 100′ isirradiated from a plurality of external radiation beam source positions,the radiation beams from the different positions provide image features(such as lines, or other marks) to the dosimeter films, which can beused to determine the trajectory of the respective radiation beams.These trajectories can then be used to determine an isocenter of theradiation treatment system in a coordinate system defined by thereference marks formed in the image. These markings can also be used tocalibrate a laser system to the image-based treatment machine isocentervalidated using phantom 100, 100′.

Since the phantom 100, 100′ includes precisely positioned fiducialmarkers, the phantom 100, 100′ is also optimal for isocenterdetermination, verification, and calibration using imaging methods, suchas but not limited to X-ray imaging methods. In an exemplary embodiment,to determine isocenter alignment using imaging methods, the phantom 100,100′ can first undergo a CT scan using a clinical simulator to generateimages of the phantom 100, 100′. FIGS. 22 and 23 illustrate a plan viewand a 3D view with two orthogonal planes, respectively, of images soobtained. The images show the fiducial markers, such as the BB markers,the transponders, pins, density inserts, etc., as well as the filminsert of the phantom 100, 100′. The images so obtained can be exportedto a treatment planning system where the insert 200 can be contoured andthe isocenter placed at its centroid based on the alignment holesvisible in the CT scan. The phantom can also be tailored for generatingMRI images. Then the phantom 100, 100′ can be securely attached to apatient support in a fixed position aligned with a set or marks, suchthat the axis of the phantom 100, 100′ is parallel to the rotationalaxis of the gantry.

The radiation treatment system is then used to generate a set of imagesof the phantom 100, 100′ at a plurality of gantry angles. The generatedimages will include the images of the fiducial markers, such as the BBsphere markers, density inserts, alignment pins, transponders, and anyother additional markers used in the phantom 100, 100′. FIGS. 24-25 areexemplary images of the phantom obtained using a kilovoltage (kV) X-raysource (FIG. 24), and a megavoltage (MV) X-ray source (FIG. 25). Bothimages show the inset cube 200, BB markers, density inserts, the threetransponders, alignment pins, and letter marking. After the images areobtained, a processing system determines the position of the firstgenerated image (e.g., the image generated at the first gantry angle)and subsequently, the positions of the fiducial markings in the image.The processing system can next form a one-to-one correspondence betweenthe projections of each of the fiducial markers in the first generatedimage and the fiducial markers themselves by, for example, determining apossible orientation of the phantom 100, 100′ that could produce thearrangement of the fiducial markers in the image, using variousdetermination techniques. The processing system can then determine thepositions of the fiducial markers in all subsequent images in the set.After the positions of the fiducial markers at all prescribed gantryangles have been obtained, the processing system can determine theactual position of the gantry at each prescribed gantry angle, as wellas the distance between the radiation source and the detector used inthe system. Various determination techniques can be used for suchpurpose.

After the positions of the gantry at all prescribed gantry angles havebeen determined, the processing system can determine the coordinate ofthe geometric center of the phantom 100, 100′ at each prescribed gantryangle. After the coordinate of the geometric center of the phantom 100has been determined, the geometric center of the phantom 100, 100′ canbe projected onto a 2D image frame for each of the prescribed angles.The projected position of the center of the phantom 100, 100′ is thencompared with a center of a projected circle in the image for each ofthe prescribed gantry angles to determine/verify the actual isocenter.If the projected position of the center of the phantom 100, 100′ is at,or is within prescribed distance from the center of the projected circlein at least two of the generated images, then the initial expectedisocenter is determined to be the actual iscocenter of the treatmentsystem. Otherwise, the initial expected isocenter position can beadjusted based on the difference. After the positions of the gantry atall prescribed gantry angles have been determined, the processing systemcan also determine the position and orientation of the gantry as well asone or more geometric parameters based on the determined positions ofthe gantry. Exemplary methods of determining the isocenter as well asone or more geometric parameters of a treatment system are described indetail in U.S. Pat. Nos. 7,844,094, 8,198,579, and are incorporatedherein by reference in their entireties.

The phantom 100, 100′ is also compatible with the so called unknowntarget point method, which is used in stereotactic treatments where astereotactic co-ordinate system is used (e.g., BRW or Leksellco-ordinate system). In such a method, the phantom 100, 100′ is usedwithout aligning the target point or isocenter accurately to thestereotactic co-ordinate system. Instead, the target point is definedbased on pre-treatment imaging, such as, but not limited to CT and MRIimaging. After the definition of the target point or isocenter, the dosedistribution is planned and applied to the phantom to determine theoffset between planned and achieved target point.

Since the phantom 100, 100′ also includes precisely positionedtransponders, the phantom 100, 100′ is also optimal for isocenterdetermination, verification, and calibration using a Calypso system. Inan exemplary method, the electromagnetic transponders, in the phantom100, 100′ can be used to communicate with Calypso localization systemsusing radiofrequency waves. The Calypso system is an electromagnetic,transponder-based, target localization and monitoring system, includingan electromagnetic array which contains an energy source that can excitethe transponders and receivers that detect each transponder's frequencyto determine its location coordinates. Each of the transponderstransmits a unique non-ionizing radiofrequency signal to the array,generating position and motion information about the target in which itis imbedded. The transponder's location is subsequently correlated tothe treatment or machine isocenter through optical reflectors on thedetector. A user interface can display the positional information bothinside and outside of the treatment room. The system can also bemultiplexed so that multiple transponders tuned at different frequenciescan be discretely detected. The electromagnetic transponders and theCalypso system can also provide target localization and monitoringduring radiation treatment delivery. During radiation treatment, thetransponders and the Calypso system can provide the cliniciancontinuous, real-time monitoring of the target and can alert theclinician when the target is outside of acceptable boundaries due toorgan motion, thereby enabling corrections during the treatmentdelivery.

Since the markings, transponders, and density inserts are formed ofmaterials which allow them to be optimally embedded into the phantom100, 100′ and thus, the outer surface of the phantom 100, 100′ is alsooptimal for optical surface monitoring. Optical surface monitoring canbe used as a verification system for patient setup and correction. In anexemplary embodiment, the phantom 100, 100′ can be exposed to alaser-based surface scanning system for patient setup and verificationand correction. For example, the phantom 100, 100′ can be exposed to a3D laser imaging system to scan its surface with laser light. The 3Dlaser imaging system can use lasers mounted on the radiation treatmentsystem or the ceiling of the room that houses the radiation treatmentunit to irradiate the surface of the phantom 100, 100′ with laser light,and a camera positioned to capture and record the reflections of theprojected laser lines. The 3D laser imaging system can then reconstructa 3D surface model of the phantom/mimicked patient/organ/target volume.The actual position of the target is then compared with that of areference image, which can be acquired either with the imaging system,or it may be generated by contouring the skin in the treatment planningCT. By comparing the two surface models, a setup correction can becalculated and used to correct the setup of the patient during radiationtreatment.

Although a laser-based surface scanning system has been described, anyother optical surface measurement systems and methods, such as, but notlimited to, an ultrasound-based optical surface measurement systems andmethods can be used. Alternatively, any distance measurement device orany other localization device can also be used in order to provide anindependent channel of position feedback, such as, but not limited tosystem as shown in FIG. 21, which enables continuous non-invasivereal-time patient motion and respiratory tracking in 3D. This isparticularly advantageous in situations where other detection systemsmay not work due to geometrical constraints.

It will be appreciated that the phantom described herein has theadvantage of providing simultaneous position verification using avariety of positioning systems, such as imaging (X-ray, for example),optical surface detection (laser, ultrasound, etc. for example), andelectromagnetic navigational system (Calypso monitoring, for example) ina single phantom. It will also be appreciated that the phantom can alsobe used to verify shifts and rotations of the phantom which have beendetermined by the use of the imaging, optical, and navigationalmonitoring systems. The phantom can also be used on a motion stage forCalypso, optical surface monitoring, and/or X-ray based motiondetermination including dosimetric verification of gated, MLC, ortreatment couch compensated radiation treatments.

It will also be appreciated that the phantom described herein can beused as an end-to-end test phantom in the field of stereotacticradiation treatments to provide a combination of imaged-based, opticalsurface based, and navigational (Calypso, for example) based positioningto determine the uncertainty of each of these systems and to positionthe phantom to the combined center.

For example, as shown in FIG. 26, the phantom 100, 100′ can besimultaneously exposed to an imaging system to generate an image of thephantom, from which a first position of the phantom is determined basedon the pattern of markers in the image. At the same time, a surfacemodel of the phantom can be generated, using an optical surface imagingmethod. A second position of the phantom can be determined based on acomparison of the generated surface model and a reference surface model.The phantom can also be continuously monitored using a Calypsomonitoring system, and a third position of the phantom can be determinedbased on the monitored position of the transponders embedded in thephantom. Based on the first, second, and third determined positions, acombined center for the phantom can be determined. The phantom, andultimately the patient, can then be positioned at the combined centerfor the treatment system. A geometric parameter, such as, but notlimited to, the treatment machine isocenter, and/or the uncertainty ofeach of these imaging and monitoring systems can also be determinedbased on the phantom positions determined using the different monitoringsystems.

In embodiments, one or more images can be generated to determine thefirst position of the phantom. The one or more images can include imagesobtained using kV, MV, CT, CBCT, SPECT, PET, MRI, or any otherapplicable imaging systems and methods.

In one example, the phantom 100, 100′ can be simultaneously exposed toan X-ray imaging system to generate an X-ray image of the phantom, fromwhich a first position of the phantom is determined based on the patternof markers in the X-ray image as discussed above. At the same time, asurface model of the phantom can be generated, using an optical surfaceimaging method. A second position of the phantom can be determined basedon a comparison of the generated surface model and a reference surfacemodel. The phantom can also be continuously monitored using a Calypsomonitoring system, and a third position of the phantom can be determinedbased on the monitored position of the transponders embedded in thephantom. Based on the first, second, and third determined positions, acombined center for the phantom can be determined. The phantom, andultimately the patient, can then be positioned at the combined centerfor the treatment system. A geometric parameter, such as, but notlimited to, the treatment machine isocenter, and/or the uncertainty ofeach of these imaging and monitoring systems can also be determinedbased on the phantom positions determined using the different monitoringsystems.

In embodiments, the X-ray image is generated using a kV, MV, CT, or CBCTimaging system.

In other embodiments, as shown in FIG. 27, the phantom 100, 100′ can beexposed to a first imaging system to generate a first image of thephantom, from which a first position of the phantom is determined basedon the pattern of markers in the first image. The phantom 100, 100′ canalso be exposed to a second imaging system to generate a second image ofthe phantom, from which a second position of the phantom is determinedbased on the pattern of markers in the second image. At the same time, asurface model of the phantom can be generated, using an optical surfaceimaging method. A third position of the phantom can be determined basedon a comparison of the generated surface model and a reference surfacemodel. The phantom can also be continuously monitored using anelectromagnetic navigational system, such as a Calypso monitoringsystem, and a fourth position of the phantom can be determined based onthe monitored position of the transponders embedded in the phantom.Based on the first, second, third, and fourth determined positions, acombined center for the phantom can be determined. The phantom, andultimately the patient, can then be positioned at the combined centerfor the treatment system. A geometric parameter, such as, but notlimited to, the treatment machine isocenter, and/or the uncertainty ofeach of these imaging and monitoring systems can also be determinedbased on the phantom positions determined using the different monitoringsystems.

In an exemplary embodiment, the first imaging system can be a kV imagingsystem, such that the first image is a kV X-ray image, and the secondimaging system is a kV imaging system, such that the second image is akV X-ray image.

In another exemplary embodiment, the first imaging system can be a kVimaging system, such that the first image is a kV X-ray image, and thesecond imaging system is a MV imaging system, such that the second imageis a MV X-ray image.

In another exemplary embodiment, the first imaging system can be a MVimaging system, such that the first image is a MV X-ray image, and thesecond imaging system is a MV imaging system, such that the second imageis a MV X-ray image.

In another exemplary embodiment, the first imaging system can be a CTimaging system, such that the first image is a CT image, and the secondimaging system is a CBCT imaging system, such that the second image is aCBCT image.

In another exemplary embodiment, a first imaging system is a kV X-rayimaging system, such that the first image is a kV X-ray image, and thesecond imaging system is a CBCT imaging system, such that the secondimage is a CBCT image.

In another exemplary embodiment, a first imaging system is a MV X-rayimaging system, such that the first image is a MV X-ray image, and thesecond imaging system is a CBCT imaging system, such that the secondimage is a CBCT image.

In other exemplary embodiments, the first imaging system can be any oneof a kV, MV, CT, CBCT, MRI, SPECT, PET, ultrasound, or any other imagingsystem including molecular imaging, and the second imaging system can beany one of a kV, MV, CT, CBCT, MRI, SPECT, PET, ultrasound, or any otherimaging system, including molecular imaging.

Any other combinations of imaging systems to obtain the first and secondimages, and ultimately the first and second phantom positions therefromcan be used. By using different imaging methods to obtain the first andsecond images, different shift values can be measured. Each of theseimaging methods gives a slightly different position value. Therefore, bymatching the images obtained using different imaging methods (i.e.,kV-kV, MV-MV, kV-MV, MV-MV, CT-CBCT, kV-CBCT, MV-CBCT) different matchvalues can be obtained, which then allows for detection of a systematicerror in the treatment system/machine. Also, using the CT-CBCT match canproduce a more accurate positioning result because there is moreinformation in the CT and CBCT images obtained that can be used for thematching algorithms used to determine a geometric parameter of theradiation treatment system/machine.

Further, although only two images are presented as generated in theillustrative embodiment, any other number of images using differentimaging systems can be used to provide an image-based position of thephantom.

It will be appreciated that the processes, systems, and sectionsdescribed above can be implemented in hardware, hardware programmed bysoftware, software instruction stored on a non-transitory computerreadable medium or a combination of the above. For example, a method forcan be implemented using a processor configured to execute a sequence ofprogrammed instructions stored on a non-transitory computer readablemedium. For example, the processor can include, but not be limited to, apersonal computer or workstation or other such computing system thatincludes a processor, microprocessor, microcontroller device, or iscomprised of control logic including integrated circuits such as, forexample, an Application Specific Integrated Circuit (ASIC). Theinstructions can be compiled from source code instructions provided inaccordance with a programming language such as Java, C++, C#.net or thelike. The instructions can also comprise code and data objects providedin accordance with, for example, the Visual Basic™ language, LabVIEW, oranother structured or object-oriented programming language. The sequenceof programmed instructions and data associated therewith can be storedin a non-transitory computer-readable medium such as a computer memoryor storage device which may be any suitable memory apparatus, such as,but not limited to read-only memory (ROM), programmable read-only memory(PROM), electrically erasable programmable read-only memory (EEPROM),random-access memory (RAM), flash memory, disk drive and the like.

Furthermore, the modules, processes, systems, and sections can beimplemented as a single processor or as a distributed processor.Further, it should be appreciated that the steps mentioned above may beperformed on a single or distributed processor (single and/ormulti-core). Also, the processes, modules, and sub-modules described inthe various figures of and for embodiments above may be distributedacross multiple computers or systems or may be co-located in a singleprocessor or system.

Features of the disclosed embodiments may be combined, rearranged,omitted, etc., within the scope of the invention to produce additionalembodiments. Furthermore, certain features may sometimes be used toadvantage without a corresponding use of other features.

It is thus apparent that there is provided in accordance with thepresent disclosure, end-to-end universal phantom for quality assuranceusing many imaging and verification modalities. Many alternatives,modifications, and variations are enabled by the present disclosure.While specific embodiments have been shown and described in detail toillustrate the application of the principles of the present invention,it will be understood that the invention may be embodied otherwisewithout departing from such principles. Accordingly, Applicants intendto embrace all such alternatives, modifications, equivalents, andvariations that are within the spirit and scope of the presentinvention.

The invention claimed is:
 1. A method of calibrating a radiationtreatment system with a single phantom based on a combination of phantompositions determined using a plurality of position monitoring methods,the method comprising: exposing the phantom to the plurality of positionmonitoring methods, the position monitoring methods comprising animaged-based, an optical surface-based, and a navigational-basedposition monitoring method; determining a first position of the phantomin the radiation treatment system by exposing the phantom to theimage-based position monitoring method; determining a second position ofthe phantom in the radiation treatment system by exposing the phantom tothe optical surface-based position monitoring method; determining athird position of the phantom in the radiation treatment system byexposing the phantom to the navigational-based position monitoringmethod; and determining a combined center of the radiation treatmentsystem based on a combination of the determined first, second, and thirdphantom positions, wherein the combined center is where a patient is tobe positioned in the radiation treatment system prior to irradiation. 2.The method of claim 1, wherein the phantom includes a plurality of dosedistribution measuring elements configured to provide dose distributioninformation of radiation dose delivered to the phantom, a plurality ofposition determining elements configured to provide position informationof the dose distribution measuring elements relative to other elementsof the phantom, and a plurality of markers including one or moretransponders, wherein the determining of the plurality of positionscomprises: generating an image of the phantom using the imaged-basedposition monitoring, and determining the first position of the phantombased on a pattern of the plurality of position determining elements andthe markers in the generated image; generating a surface model of thephantom using the optical surface-based position monitoring, anddetermining the second position of the phantom based on a comparisonbetween the generated surface model and a reference surface model; andtracking the positions of the transponders in the phantom using thenavigational-based position monitoring method, and determining the thirdposition of the phantom based on the tracked positions of thetransponders.
 3. The method of claim 1, wherein the phantom is exposedto the plurality of position monitoring methods simultaneously.
 4. Themethod of claim 1, wherein the phantom is exposed to the plurality ofposition monitoring methods consecutively.
 5. The method of claim 1,wherein the generating an image of the phantom using the imaged-basedposition monitoring includes generating one or more images of thephantom using an X-ray imaging system, an MRI system, a SPECT system, aPET system, a CT system, or an ultrasound imaging system.
 6. The methodof claim 1, wherein the generating a surface model of the phantom usingthe optical surface-based position monitoring includes generating asurface model of the phantom using one of a 3D laser imaging system oran ultrasound based scanning system.
 7. The method of claim 1, whereinthe tracking the positions of the transponders in the phantom using thenavigational-based position monitoring method includes tracking thepositions of the transponders using a Calypso monitoring system.
 8. Themethod of claim 2, further comprising generating a second image of thephantom using a second imaged-based position monitoring, and determininga fourth position of the phantom based on a pattern of the plurality ofposition determining elements and the markers in the generated secondimage, wherein a calibrated position for the phantom in the radiationtreatment system is determined based on the determined first, second,third, and fourth phantom positions.
 9. The method of claim 8, whereinthe first image is a kV X-ray image and the second image is a kV X-rayimage.
 10. The method of claim 8, wherein the first image is a kV X-rayimage and the second image is a MV X-ray image.
 11. The method of claim8, wherein the first image is a MV X-ray image and the second image is aMV X-ray image.
 12. The method of claim 2, wherein the plurality of dosedistribution measuring elements includes one or more film inserts,and/or a dosimetric gel insert.
 13. The method of claim 12, wherein theone or more film inserts includes a radiochromic film and/orthermoluminescent dosimeter film, and/or an optically stimulateddosimeter film.
 14. The method of claim 12, wherein the plurality ofdose distribution measuring elements includes two film insertspositioned in orthogonal planes.
 15. The method of claim 8, furthercomprising determining a geometric parameter of the radiation treatmentsystem based on the determined calibrated position for the phantom. 16.The method of claim 15, wherein the geometric parameter comprises one ofan uncertainty of at least one a position monitoring system used for theplurality of position monitoring methods, a source-to-imager distance, asource-to-axis distance, an axis of rotation, a center of rotation, apiercing point, or an isocenter of the radiation treatment system. 17.The method of claim 8, further comprising determining a treatmentposition of a patient based on the determined calibrated position of thephantom.
 18. The method of claim 1, wherein the phantom includes acombination of different dosimeters in a single dosimetric insert tothereby measure relative dose distribution and absolute dosedistribution.
 19. The method of claim 2, wherein the plurality of dosedistribution measuring elements, the plurality of position determiningelements, and the plurality of markers include different materialshaving different densities in order to provide substantially identicalmarker contrast in kV and MV images.
 20. The method of claim 8, furthercomprising validating the radiation treatment system using thecalibrated phantom position.